Reversible fluorescence modulation based on photochromic diarylethene and fluorescent coumarin

A fluorescence switch by the photoisomerization of a photochromic compound in CH₃CN and in a polymer film using a bistable photochromic (1,2-bis(2-methylbenzo[b]thiophen-3-yl) hexafluorocyclopentene) (BTF6) and a fluorescent 3-(2-benzothiazolyl)-7-(diethylamino) coumarin (coumarin6) was demonstrated. Because only the closed form of BTF6 serves as a fluorescence quencher of coumarin6, and the read (406 nm), write (254 nm), and erase (>500 nm) wavelengths are well-separated, a reversible modulation of the fluorescence of coumarin6 with high contrast and high sensitivity is expected to be realized. This system may represent an alternative to the fluorescence switches that are based on covalent systems in the potentially long-term optical data or image storage schemes utilizing luminescence intensity readout.